Electrical relay and circuit.



No. 668,554. Patented Fab. I9, |90I..

A. m. BULLARD & L. A. FALK. ELECTRICAL RELAY AND CIRCUIT.

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I 6 ode UNITED STATES PATENT OFFICE.

ALBERT M. BULLARD, OF SOMERVILLE, AND LOUIS A. FALK, OF BOSTON, MASSACHUSETTS, ASSIGNORS TO THE AMERICAN BELL TELEPHONE COM PANY, OF BOSTON, MASSACHUSETTS.

ELECTRICAL RELAY AND CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 668,554, dated February 19, 1901.

Application filed December 3, 1900. Serial No. 38,477. (No model.)

To all whom it may concern: within the field of the two end poles, respec- 56 Be it known that We, ALBERT M. BULLARD, tively; but by making the rearward arm a residing at Somerville, in the county of Mid-. little longer or heavier than the other a nordlesex, and LOUIS A. FALK, residing at Bosmal inclination is imparted to it, so that the ton, in the countyof Su'lfolk, State of Massaarmature is overbalanced rearwardly, and

chusetts, have invented certain Improvewhile its hinder end is in close juxtaposition ments in Electrical Relays and Circuits, of to the approximate pole, the forward endis as which the followii'ig is a specification. far away from the forward pole as is permit- This invention relates to electromagnetic ted by the range of armature oscillation.

1o apparatus, and particularly to relays and ci'r- Thus when a current impulse passes through cuits controlling and controlled by them. Its both coils the attraction exerted by the core object is to provide a single relay capable of upon the rearward end of the armature is, responding to either intermittent or continuby reason of its closer proximity to the pole, ous electric currents traversing a main cirmuch greater than the opposing attraction 15 cuit with which it may be connected and exercised upon its forward end by the forwhich under the influence of the said curward pole, and the armature consequently rents is capable of selectively controlling remains at rest, being practically locked either or both of two independent local ciror retained in its normal position by the precuits for the operation of the apparatus assoponderating influence of the rear pole. The

20 ciated therewith or contained therein. lighter armature is suspended or fulcrumed I The relay of this invention has two indealso at or near the intermediate pole, but expendent armatures of diverse inertia. One tends therefrom in one direction only-viz., of these (the heavier) is irresponsive to into the forward end pole, and is therefore terrupted or intermittent currents, which in-' subject to the action of the forward exciting- 25 deed, so far as they affect it at all, tend to coil only. Since this armature is not conmainiain its quiescence or normalor resting trolled by the rear coil, it is responsive to position, but responds to the passage through any current sufficiently strong traversing the the main circuit of a continuous or steady front coil and is consequently responsive current or to a current impulse which is so not only to a steady current passing therein,

30 far protracted thatits following currents and but, having littleinertia,to a rhythmically-inintermissions do notin anysense followoneanterrupted current also, moving to its forward other-with such rapiditythattheycan properly limit on the passage of the impulse and fallbe said to be rhythmical. The lighter armaing back promptly on the intermission. ture is arranged to be responsive either to a Referring to the functions of the two excit- 35 steadyor conti n nous current or toarhythmicing-coils, we term the front coil the actuatally-interrupted current. To act upon these ing-coil and that on the rear section ofthe armatures, the relay is provided with an iron core a locking-coil. core having forward and rearward terminal Both armatures are provided with local-cirpoles or polar ends and an intermediate pole cuit contactswhich are controlled by their os- 0 or pole-piece, the said core being wound with cillations, the said contacts being united by lwo magnetizingcoils surrounding the forthe forward motion of the corresponding arward and rearward sections, respectively mature and separating on the recession of the formed between theintermediate and the two armature. By this means our relay is enend poles. The said coils are in series with abled to do work heretofore requiring the em- 5 one another and are adapted for connection ployinent of two separate relays that is, it

in a main circuit. The heavier armature is independently controls two separate local cir- 5 poised or fulcrumed at or near its middle at cuits or connecLions-closing one of said local the intermediate pole, and its ends extend in circuits with each successive impulse of an opposite directions to points in front of and intermittent current and closing the other whenever theinterruptions cease and the on rrent remains continuous or steady.

To bring about the requisite motion of the main or heavy armature in its proper time, we provide means controlled by the oscillations of the lighter armature for withdrawing the locking-coil from the circuit when a con tinuous current passes. The said locking coil is, indeed, so withdrawn during the latter portion of each impulse of the intermittent current; but the transient withdrawal of the locking-coil under these conditions is so immediately followed by an intermission of current that the excitement of the front coil also at once ceases and the main armature does not move. Thus to bring about the operation of said armature our invention requires that the locking-coil shall first be withdrawn from the working circuit or deprived of current and that during such condition of the retaining-coil a current shall continue to flow through the actuating-coil. This occurs during the passage of a continuous current. In the main circuit which contains the said coils we provide a source of current, means for interrupting the current rhythmically, and means for withdrawing the said interrupting apparatus to permit the steady flow of current.

Our invention is primarily designed for use in automatic telephone-exchanges, wherein heretofore the practice has been to employ two relays to close independent local circuits at the central station, including, respectively, a selecting-magnet and a connecting-magnet. When so employed to produce the intermittent current necessary for the exclusive operation of the lighter relay-armature, a rhythmical interrupter or circuitbreaker at the substation is introduced into the main circuit, which also includes the central battery, and the requisite succession of current impulses is thus created. These in due season are followed by the establishment in the circuit of a steady current, and this is brought about when the substation-telephone is removed from its switch-hook, the circuit being thereby closed through the said telephone, and pursuant to the said continuous current the heavy relay-armature is operated.

In the drawings which accompany this specification, Figure 1 is an elevation of one form of our relay. Figs. 2 and 3 are respectively a top and side view of another and in some respects preferable form of the said relay. Fig. 4 is an end view of the form illustrated by Figs. 2 and 3. Fig. 5 shows crosssections of the two armatures on the line two of Fig. 3. Fig. 6 is a diagram showing the connections of the relay as associated with a substation-circuit of an automatic exchange system.

Referring for the present to Figs. 1 and 6, R is the relay, shown as being mounted horizontally and secured at the rear end by the bolt b to a bracket B. K is the iron core, having polar ends P P and an intermediate pole or pole-piece p, which may also serve as a partition, dividing the core into front and rear sections K K and likewise by giving its upper side a knife-edge maybe utilized as an armature-fulcrum f. The core may be in one piece from end to end or, if desired, the front and back sections may be separate, but secured end to end, the front section, however, in either case being preferably smaller in cross-section than the rear, since it is desired that the latter shall be sluggish and the former relatively rapid in operation. The front polar end is shown as being formed of an iron strip y, bolted to the core and turned at a right angle at the top and bottom ends to overlap the coil-spool; but any preferred construction, such as the plate form of the rearward polar end, may readily be adopted.

A is an armature of considerable inertia fulcrumed atf and extending by arms in and n to the rear and front polar ends, respectively. It is made heavier at the rear end either by making that arm longer than the other or of greater cross-section than the other or, as indicated in Fig. 5, by making holes or recesses in the front arm a or otherwise lightening the same. Guidepins 3 and 5 are secured to the polar ends and pass loosely through holes in the armature, the requisite range being determined for the oscillations of said armature by threading the ends of said pins and fitting them with adjustable nuts, so that the said nuts serve as limitstops. The lower armature Ct is much lighter and smaller, and its inertia is therefore much less. It is fulcrumed at one end 71/ in a support 1', attached to an arm j, secured at or near to the intermediate pole p, and extends by its free end to a point in front of the front pole P. This armature has a guide-pin and limit-stop 4.

The heavy armature A controls local-circuit contacts 0 and 0 the latter being fixed and the former carried by the armature it self, and the light armature a in like manner controls movable and fixed local contacts (Z and (1 The said fixed contacts 0 and (Z are mounted in metal strips or plates insulated from one another and from the core by suitable insulating-layers, but mechanically secured to said core by the bolt 1 The exciting-helices r and s of the relay are adapted for connection in a main circuit E and are in series with each other in said main circuit,which, entering by conductor 6, passes through the actuating helix or coils, the conmeeting-conductors 7 and 8, and the retaining-coil r in succession, leaving the latter by conductor 9 and leading thence to the source of current S, the other conductor 26 of said main circuit being extended from the other pole of said source. The battery S may also supply current for a local circuit M, controlled by the local points (Z d of the lighter armature a and including a relay R This circuit, starting from the battery, passes by conductor 16, through relay R to conductor 12, contacts (1 and d, armature a, and through the support therefor, the core, and the framework generally to the common return-conductor 10. It is normally open, but is closed when by the forward motion of armature a the points d d are united.

N is another local circuit, which may contain a relay R or, in fact, any desired appliance, such as an indicatororalamp, and which also may be supplied with current by the battery S. This circuit, starting from said battery,passes,by way of conductor 16, conductor 17, relay R conductor 13, contact-points c c, and armature A, to the metallic core and framework, and thus to common return 10. This circuit also is normally open and is controlled by armature A, being closed when the points 0 c are brought into contact by the forward movement thereof.

Z is a shunt-circuit constituting means for the control of the locking-coil r of the relay. It is normally open, and the coil 7" is therefore in the main circuit; but its continuity is controlled by the relay-points e e of relay R and when these are brought into contact the shunt-circuit is closed and the coil 1" practically withdrawn from the main circuit, so that currents passing through said main circuit and the forward coils no longer pass through the coil 7" also, but through the shunt-conductors l4 and 15, which short-circuit the said coil r by passing from the point g on one side of coil 1" to the point g on the other through the contacts 6 c of relay R It is manifest that, if desired, the lighter armature a of the relay R of our invention could be made to control the shunt-circuit Z directly by its local contacts (1 01 instead of employing these contacts to close an intervening circuit acting upon the shunt by means of a second relay. If an intermittent current or an appropriate series of current impulses be transmitted through the relay of our invention, the light armature a will respond to each impulse and will be attracted forward, bringing the contacts 01 d togetherand closing the local circuit M; but the heavy armatureA will not respond,forthe said current impulses traverse coil r as well as coil 8, and though undoubt edly attraction is thereupon exercised on said armature by both poles P and P that exerted by the rear pole P is the stronger, since the end m of the armature is close to that pole and since, therefore, all that the said pole P has to do is to maintain the armature in the resting position it normally occupies. Consequently during the transient impulses of current through both coils armature aresponds, but armature A does not; but when armature 0t closes its contacts d d" the operation of relay R (if such relay be employed) or the operation of said contacts directly closes the shunt circuit transiently around the retaining-coil t. When this occurs, the heavy armature A becomes acted upon, like the armature a, by the front coil 3 alone, and would operate were it not that, the intermission of current closely following the impulse thereof, the attraction due to the said front coil has ceased, and this, together with the mechanical inertia of the armature and the electrical inertia of the core-section K prevents the said armature from being moved during the brief periods wherein the shunt Z is closed while an intermittent current is passing through the circuit. The succeeding current impulse thus finds the shunt again opened and the Winding?" in the main circuit, and again the armature A is retained; but if instead of such intermittent current a continuous current flows in the main circuit, so that the light armature ct once attracted into its forward position stays there for an interval of time at all protracted, the points d and (31* remain in contact, and the shunt-circuit consequently remains closed, practically withdrawing the relay-coil r from the main cir cuit. The heavy armature A no longer held by the forces combining to maintain its quiescence and now acted uponby the coil salone oscillates into its operative position, the end 'lt approaching more closely to pole P, and thus bringing the points 0 0 into contact and closing the local circuit N. Apparatus for producing this cycle of operations is indicated in the diagram Fig. 6, the central-station portion U of which, comprising the relay of our invention, the central source of current, the auxiliary relays R andR", and the local and shunt circuits, has already been described.

V is a substation of the main circuit E. Normally the telephone is on its switchhook, as shown, the circuit in that case being conductively open in the condenser 7c.

I is a rhythmical interrupter of any wellknown construction connected in a branch 18 of the circuit. To send recurrent impulses, the said interrupter is operated and causes a succession of alternate current impulses and intermissions in the circuit, which affect our relay and the apparatus controlled thereby in the manner described. When the appropriate number of pulsations for any particular occasion has been sent, the operation of the interrupter ceases and the telephone 75 is removed from the hook, closing the main circuit and permittingacontinuous or steady current to flow therein from the source S. When our relay is operated in association with such a central-battery automatic exchange appara tus as has been indicated and generally de scribed herein, it is found advantageous to so adjust or arrange the substation-circuitinterrupting device as to produce the intermittent current impulses at a rate of about ten per second.

The form of relay illustrated by Figs. 2 and 3 does not differ in principle from that already described. Its construction, however, provides that the lighter armature a aswell as the heavier, A, shall be fulcrumed on the knife-edge at the intermediate pole p, a cap w being placed over both to prevent displace- IOO ment. The said armature a, though still extending from its fulcrum to the forward p0lepiece P, is fitted with a rearward extensionpiece d of brass or like non-magnetic metal or alloy, to aid in maintaining its poise. The weight of the heavier armature is distributed as in the former case, the fulcrum preferably being slightly nearer to the front pole P than to the rear pole P This gives the armature the required normal bias toward the said rear pole-piece and aids in providing a longer coilspace for the helix 7', this being found generally desirable. Both armatures being above the coil, the contact-points c and d are likewise both above, a separating-pin 0 being placed between the armature ends. The whole is mounted on a base-board 7.

7e claim l. A relay comprising an iron core; an exciting-coil therefor consisting of front and rear sections in series; an armature of slight inertia in the field of the front coil-section responsive to currents passing through said front coil-section regardless of the condition of the other; and asecond armature of greater inertiain the field of both coil-sections, adapted to be held in its normal position when currents are passing through both coil-sections, but to be responsive by attraction into its working position, on the passage of current through the front coil-section only; substantially as set forth.

2. In a relay, the combination of an iron core having terminal poles, and divided by an intermediate pole into two sections; two magnetizing-coils in series wound over the said two core-sections respectively; an armature extending between the said terminal poles, fulcrnmed intermediately, and biased or inclined toward the rear terminal pole, the same being held in its normal position by the preponderating influence of the said rear pole when an exciting-current is passed through both coils, but adapted to move toward the front pole and into its operative position on the passage of a steady current through the coil of the front coil-section only; a lighter armature extending from a fulcrum at the said intermediate pole to the front terminal pole only, and made to be responsive to the passage of an exciting-current through the coil of the front core-section, regardless of the condition of the other; and independent sets of local-circuit contacts controlled by the said arlnatures respectively; substantially as described.

8. In a relay, the combination of a single magnetic core with polar extremities, and divided into front and rear sections by an intermediate polar partition; a main armature poised intermediately and adapted to oscillate between said polar extremities, but normally approximating toward that of the rear section; a lighter armature suspended by one end at the said intermediate pole and having its other end extended to the front polar extremity of said core; a magnetizing-coil surrounding the said front section of said core, and adapted when traversed by an excitingcurrent to cause said core to exercise attraction on both armatures; a second excitingcoil in series with the first, surrounding the rear section of said core, and adapted when traversed by an exciting current to cause said core to exercise attraction on the main armature alone, tending to maintain the quiescence thereof; circuit-closing relay-points controlled by the said lighter armature; and means controlled by said relay-points for withdrawing the second or rear section-coil from the circuit; substantially as and for the purposes specified.

1-. The combination in a relay, of an electromagnetic core adapted to have end poles and an intermediate pole; a main armature therefor poised near its middle and extended between said end poles, but unbalanced and normally inclining toward the rearward, and away from the forward end pole, but capable of oscillating into a reversed or forward position; local contacts normally separated but adapted to be united by said armature when attracted to its forward position; an actuating-coil for the forward pole of said core and a retaining or locking coil for the rearward pole thereof, in serial circuit with each other, the formeroperating to swing the said armature into said forward position, and the latter acting to retain said armature in its normal position; with a lighter armature acted upon by the said forward pole and actuating-coil only; and means controlled by said lighter armature for short circuiting said retainingcoil, and for maintaining said short circuit as long as the current actuating said lighter armature persists; whereby the main armature is made irresponsive to an interrupted current, and responsive to a continuous or steady current passing in the circuit of the actuating-coil; substantially as specified.

5. The combination in a relay, of an iron core having terminal poles, and an intermediate pole; an armature fulcrumed at the intermediate pole and extending between the terminal poles, the same gravitating normally toward one of the said terminal poles; a second and lighter armature also fulcrumed at said intermediate pole, and extending therefrom to one only of said terminal poles; two sets of local contacts controlled by the said armatures respectively; an exciting-coil comprising two serially-connected sections wound over said core between the intermediate and the terminal poles respectively; and a shuntcircuit for one of said coil-sections controlled by the local contacts of said lighter armature; substantially as and for the purposes set forth.

6. The combination of a main circuit; a source of current contained therein; and means for establishing in said circuit either a continuous or a rhythmically-intermittent current from said source; with a relay compris ing a sluggish armature, an actuating and a retaining coil in series in said circuit the former acting to move said armature, and the latter acting in opposition and operating to prevent the movement of said armature during the passage of intermittent current in said main circuit, an auxiliary armature of lesser inertia under the influence of the actuatingcoil only and hence responsive to all currents in said main circuit, and two sets of relay-contacts controlled by the said armatures respectively the members of each being united when the controlling-armature has been moved by said actuating-coil; a local circuit including the said relay-contacts of the sluggish armature; and a shunt-circuit of the relay retaining-coil, controlled directly or indirectly by the relay-contacts of the lighter armature, and adapted to be closed thereby, and to free the sluggish armature of said relay on the passage of continuous or steady current in the main circuit substantially as set forth.

7. The combination of a main circuit; a source of current; and a device for rhythmically interrupting the current of said source included therein; and means at a station of said circuit for withdrawing the said interrupter therefrom, and thus leaving the current steady; with a relay comprising a core; two armatures, one placed in operative relation to both terminal poles of said core, and the first in operative relation to one only of said poles; a retaining-helix in said circuit acting on said core in such manner as to prevent the movement of the first-named armature; a second helix serially connected with the said retaining-coil in said circuit acting on said core in'such manner as to operate the second armature,and to operate the first when freed from the influence of said retaining-coil; independent local contacts for each of said armatures; and a normally open shunt-circuit around the retaining-helix controlled by the local points of said second armature; whereby the first armature is prevented from operating during the passage of interrupted or intermittent currents, but enabled to operate on the passage of a steady current; substantially as set forth.

In testimony whereof we have signed our names to'this specification, in the presence of two subscribing witnesses, this 1st day of December, 1900.

' ALBERT M. BULLARD.

LOUIS A. FALK.

Witnesses:

GEO. WILLIS PIERCE, JOSEPH A GATELY. 

